Sprinkler systems for turf irrigation are well known. The typical system includes a plurality of valves and sprinkler heads in fluid communication with a water source, and a centralized controller connected to the water valves. At appropriate times the controller opens the normally-closed valves to allow water to flow from the water source to the sprinkler heads. Water then issues from the sprinkler heads in predetermined fashion.
There are many different types of sprinkler heads, including above-the-ground heads and "pop-up" heads. Pop-up sprinklers, though generally more complicated and expensive than other types of sprinklers, are thought to be superior. There are several reasons for this. For example, a pop-up sprinkler's nozzle opening is typically covered when the sprinkler is not in use and is therefore less likely to be partially or completely plugged by debris or insects. Also, when not being used a pop-up sprinkler is entirely below the surface and out of the way. As the present invention is primarily directed toward pop-up heads, the remaining discussion will focus on this type of sprinkler.
The typical pop-up sprinkler head includes a stationary body and a "riser" which extends vertically upward, or "pops up," when water is allowed to flow to the sprinkler. The riser is in the nature of a hollow tube which supports a nozzle at its upper end. When the normally-closed valve associated with a sprinkler opens to allow water to flow to the sprinkler, two things happen: (i) water pressure pushes against the riser to move it from its retracted to its fully extended position, and (ii) water flows axially upward through the riser, and the nozzle receives the axial flow from the riser and turns it radially to create a radial stream. A spring or other type of resilient element is interposed between the body and the riser to continuously urge the riser toward its retracted, subsurface, position, so that when water pressure is removed the riser will immediately proceed from its extended to its retracted position.
The riser of a pop-up sprinkler head can remain rotationally stationary or can include a portion which rotates in continuous or oscillatory fashion to water a circular or semicircular area, respectively. More specifically, the riser of the typical pop-up rotary sprinkler includes a first portion which does not rotate and a second portion which rotates relative to the first (non-rotating) portion. The present invention will be described in terms of a pop-up sprinkler of the rotating type, although those skilled in the art will recognize that the invention could be advantageously applied to any type of pop-up sprinkler.
The rotating portion of a pop-up sprinkler riser typically carries a nozzle at its uppermost end. Several different nozzle sizes are usually available so that the appropriate flow rate can be selected for any given water pressure. Although nozzles have historically been installed in the risers by manufacturers, they are usually configured so that they can be removed in the field. Nozzle removal is necessary to permit flushing of the water lines following initial installation. Also, it may be necessary to unplug the sprinkler nozzles should they become clogged with debris, or to replace a nozzle which has been internally worn by abrasives (e.g., sand) in the water. Nozzle abrasion is a real problem whenever well water is used for irrigation. Some of the northeastern states and Florida particularly suffer from this problem. Finally, a nozzle may be replaced simply to achieve a different water flow rate. This may be necessary if the water pressure changes significantly, or if it is desirable to change the sprinkling pattern or coverage.
Prior art pop-up sprinklers, although generally satisfactory for their intended use, included nozzles which were difficult to remove, however. One would typically have to grasp the riser and pull it out of the sprinkler body against a significant spring force. Then, while holding the riser in its extended position, the nozzle would be removed. This process was repeated in reverse to replace the nozzle. When a large number of nozzles had to be replaced this procedure became overly burdensome.
For example, U.S. Pat. No. 3,655,132, issued to R. F. Rosic, discloses a rotary pop-up sprinkler which includes a nozzle block removably pinned to the riser assembly. While the Rosic rotary sprinkler is desirable in that it permits removal and replacement of the nozzle module without having to replace the entire riser assembly or sprinkler head, it is disadvantageous due to the fact that the nozzle module cannot be removed without first pulling the riser assembly out of the sprinkler body. Also see U.S. Pat. No. 2,253,979, issued to P. De Lacy-Mulhall, which discloses a sprinkler head of the pop-up rotary type. The nozzles of this sprinkler appear to be replaceable, but in order to access the nozzles the riser must be extended.
One prior art sprinkler addresses the nozzle removal problem, however. U.S. Pat. No. 3,149,784, issued to J. R. Skidgel, discloses a pop-up rotary sprinkler having nozzles which are seemingly removable through holes in the cover plate. Thus, the Skidgel sprinkler design apparently avoids the problem of having to manually extend the riser to change the nozzles. However, Skidgel's nozzles are continually exposed to the elements, and can be clogged by debris and/or insects.
The present invention is directed toward the problem of removal of the nozzle from a pop-up sprinkler. More particularly, the present invention permits removal of a nozzle without extending the riser, but at the same time protects the nozzle when the riser is retracted within the sprinkler body.